A previously unreported study out of the Oklahoma Geological Survey has found that hydraulic fracturing may have triggered a swarm of small earthquakes earlier this year in Oklahoma. The quakes, which struck on Jan. 18 in a rural area near Elmore City, peaked at magnitude 2.8 and caused no deaths or property damage.

The study, currently being prepared for peer review, follows news today that Cuadrilla Resources, a British shale gas developer, has found that it was “highly probable” its fracturing operations caused minor quakes of magnitude 2.3 and 1.5 in Lancashire, England. The Cuadrilla study could complicate the expansion of hydraulic fracturing for shale gas in risk-averse Europe, where France has already banned the practice.

That’s E&E News PM on the twin earth-shaking reports on an emerging concern about fracking, which involves blasting massive amounts of water through rock under high pressure to get the gas out.

If this had been happening to some renewable energy technology it would be all but fatal. Oh, wait, it was: “Fears of induced minor earthquakes have already complicated development of geothermal energy in regions like Nevada and Switzerland.” See also LiveScience, “Earthquake Concerns Shake Geothermal Energy Projects.”

[The UK study] Geomechanical Study of Bowland Shale Seismicity, came out today, and found that it was “highly probable” that Cuadrilla’s activity did cause the shocks. It reckons they were caused by an “unusual combination of geology at the well site coupled with the pressure exerted by fracking”.

Mike Stephenson of the British Geological Survey says he is not surprised at the report’s conclusion that these shocks were connected to Cuadrilla’s activities — BGS’s analysis already showed that the shape of the seismic traces the two earthquakes made were similar to each other, suggesting that they had the same trigger….

So this is certainly a set back for the shale publicity machine. Beyond that, there are real questions here for Cuadrilla. Compared to drilling for conventional natural gas, shale extraction requires digging many more wells to get at the gas. Cuadrilla has already said it wants to drill at 400 sites in Lancashire. If fracking at one well can cause two small shocks, that must raise concerns about what fracking at 400 points would do.

E&E News has more details on the Oklahoma case:

Triggered earthquakes have also been tied to the long-standing American practice of injecting wastewater into wells. However, most geologists doubt that fracturing can muster similar seismic activity.That is exactly what the Oklahoma seismologist who prepared the study, Austin Holland, told the resident reporting the quakes, who mentioned that fracturing had begun the day before at a nearby well. Earthquakes are typically triggered by stresses more prolonged than those found in fracturing, a reason it is generally held in the geology business to cause seismic events of magnitudes less than zero.

But out of due diligence, Holland began examining the suite of almost 50 seismic events that followed the 2.8-magnitude quake. The majority of the microquakes struck within 3.5 kilometers of the fracturing well, Picket Unit B 4–18. The quakes were shallow and fit well in time and space with the start of fracturing in the nearby well. The geophysical model fit, too.

“The more and more we looked at it, it looked like it was a correlation,” Holland said.

In January, the Department of Energy set up a committee to examine the full range of environmental impacts of fracking. I testified to the members and, in addition to raising the issue about methane leakage and global warming, I brought up the earthquake issue.

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The committee said that they were indeed aware of this issue and ultimately the seven-member panel released a report of environmental guidelines for the natural gas industry, which included call on more research on “Understanding induced seismicity triggered by hydraulic fracturing and injection well disposal.”

I don’t consider this to be one of the 2 or 3 biggest concerns around fracking, but it is certainly one that bears considerably further study.